Over the years, a number of techniques for making plant nutrients and moisture available to seeds and seedlings have been proposed.
One of these heretofore proposed techniques involves the use of a hygroscopic or moisture absorbent composition to retain moisture which is later released for uptake by the seeds of seedling. Specific, representative techniques of this character are described in U.S. Pat. Nos. 3,710,510 issued 16 Jan. 1973 to Tully et al. for PLANT GROWTH MEDIA AND METHODS and 4,540,427 issued 10 Sep. 1985 to Helbling for METHOD FOR IMPROVING WATER RETENTION PROPERTIES OF SOIL AND AN AGENT FOR PERFORMING THIS METHOD. This approach to promoting plant growth and survivability has the obvious, and significant, drawback that it does nothing to ensure that the plant nutrients needed for survivability and growth are made available to the seed or seedling being grown.
Self-contained systems which, at least theoretically, have the potential for remedying this lack and making both nutrients and moisture available to seeds and seedlings are disclosed in U.S. Pat. Nos. 3,373,009 issued 12 Mar. 1968 to Pruitt et al. for NUTRIENT PLANT MATRIX; 3,973,355 issued 10 Aug. 1976 to McKenzie for SELF-CONTAINED HYDROPHILIC PLANT GROWTH MATRIX AND METHOD; 4,055,974 issued 1 Nov. 1977 to Jackson, Jr. for DISINTEGRATABLE FERTILIZER TABLET; 4,402,725 issued 6 Sep. 1983 to HELLER et al. for FERTILIZERS; and 4,579,578 issued 1 Apr. 1986 to Cooke for FERTILIZERS.
While the approaches to promoting plant growth and survivability disclosed in the foregoing patents do have the potential for providing both moisture and plant nutrients, it is not clear that they have the capability of doing so effectively or at a cost which would allow them to be used on a large scale.
These drawbacks become particularly acute in applications such as silviculture in which a high degree of survivability is needed for reforestation to be economically practical.
At present, the most common method of replanting logged-over areas is with bare root or container grown seedlings. These are nursery grown for a specific period of time. Upon reaching an acceptable size and point in their growth, the seedlings are removed from the containers in which they were grown or lifted from the nursery field and either placed in cold storage or transplanted directly at the site. Planting is normally done for a short period of time in the Spring and occasionally in the Fall.
During the first year of outplanting, the seedling rarely experiences any growth and at best struggles to survive the transplant shock. The root system is busy attempting to re-establish itself in an alien soil often void of any nutrient amendments, and it is vulnerable to any moisture shortage. If the seedling survives, it will most likely enter into a premature dormancy stage and experience a total lack of growth in the first year.
During the second year, conditions should improve. However, the transplanted seedling still has much to overcome before it is assured of developing into a potential sawlog. At this stage, the seedling is rooted in native soil that rarely has optimum nutrient and moisture levels. In addition, the seedling must compete with established, more aggressive native plants for moisture and nutrients. It will commonly take three to ten years of struggle before the transplant will be established as the dominant species on the site.
Thus, economically viable systems which will enable a seedling to survive transplant shock and develop into a healthy, dominant plant are of considerable economic importance to, for example, those areas of the world which have a lumber industry.